This invention relates to a body construction for a check valve or the like for carrying a fluid or fluid flow and in particular to up-stop structure for the respective members of a bi-petal check valve wherein strong unidirectional surges of fluid flow must be accommodated.
A check valve of the character indicated provides a seat post which extends diametrically across the section of flow accommodation in a pipe or conduit, thus dividing the flow and providing two like opposed generally semi-circular seat openings to share the fluid flow. And separate valve members are hinged back-to-back on a common axis parallel to and at downstream offset from the seat post, with provision for resiliently loading the valve members to their normal seated position of closing the respective seat openings. Sudden surges of fluid flow in the downstream direction open the valve with such force that the valve members can have mutually destructive impact unless measures are taken for avoiding member-to-member contact upon valve opening. And the prior art includes various such measures, including independent valve-body upstop referencing for each of the valve members (U.S. Pat. No. 4,230,148), and torsion-spring retarders for the valve members as they approach full-open position (U.S. Pat. Nos. 4,351,358 and 4,249,567).
All of the up-stop or retarding structures of which I am aware exhibit various deficiencies, not the least of which is that their retarding or impact-resisting force is relatively local, in application to the respective valve members. One may generalize by observing that the prior-art structures have relied upon essentially point contact with the opening valve members, with the result that the momentum of opening valve members must be asymmetrically absorbed, with ultimately destructive effect upon the valve members and/or their hinging and upstop structures.